Grinding device comprising a disc-shaped grinder and guide faces for the tool to be ground



Aug. 8, 1967 c. .JAGER 3,

GRINDING DEVICE COMPRISING A DISC-SHAPED GRINDER AND GUIDE FACES FOR THE TOOL TO BE GROUND Filed July 21, 1964 2 Sheets-Sheet l L 1 f in" W Q 111 29 Q :4! I/17'/ I r 15 I --22 i l P 20 I 5 8 F AGENT Aug. 8, 1967 c JAGER 3,334,446

GRINDING DEVICE COMPRISIN A DISC-SHAPED GRINDER AND GUIDE FACES FOR THE TOOL TO BE GROUND Filed July 21, 1964 2 Sheets-Sheet 2 //21 2s 39 N V INVENTOR. CORNELIS JAGER United States Patent 3,334,446 GRINDING DEVICE COMPRISING A DISC-SHAPED GRINDER AND GUIDE FACES FOR THE TOOL TO BE GROUND Cornelis Jager, Drachten, Netherlands, assignor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed July 21, 1964, Ser. No. 384,102 3 Claims. (Cl. 51-128) The invention relates to a grinding device for knives, scissors and similar tools, in which guide faces are provided for supporting the tools to be ground.

The known supporting members for the tools during the grinding process are usually formed by simple plates, the shape and mounting of which are mainly adapted to the requirements of factory machinery.

The invention has for its object to provide a grinding device which is suitable, also with respect to the guide faces, for household use, where the instrument is to be manipulated by laymen, so that the guiding must be such that errors in grinding are excluded. While the shape must be adapted to the household requirements.

The invention is characterized in that one of the guide faces is formed by the wall of the motor housing leading to the grinder, there being arranged an extension piece above said wall, a lower wall of said piece forming a slot with the wall of the housing, the extension 'piece itself being provided with a slot, the walls of which form guide faces leading towards the disc-shaped grinder.

Consequently, with a simple housing made from moulded material for example a synthetic substance, an external wall portion thereof may be simply used as a guide face. While the extension pieces matches the required conditions.

The object of the invention is advantageously realized in an embodiment characterized in that the upper wall of the motor housing on either side of the head face of the grinding disc forms two guide faces leading to the grinding disc. While above the same there is provided an extension piece, the lower side of which are downwardly inclined towards each other, the central part being provided with a transverse slot cutting the extension piece above the head face of the grinding disc, the extension piece being secured to the motor housing on the side opposite said cutting.

Thus the upper face of the housing as a Whole forms a bed with fiat walls inclined towards the grinding disc. While the extensions piece can be accommodated in the bed, so that a compact construction desirable for household apparatus without parts projecting from the housing is obtained, whereas it is possible to grind knives in one slot and scissors in the slot of the extension piece, which scissors have a larger cutting angle than knives. Separate guide faces for knives and scissors are known but they are made and mounted in a quite different manner, which involves the known disadvantages. The construction in accordance with the invention ensures in a simple manner that the surface of the grinding disc is always engaged in the correct manner without the risk of one part of the cutting edge coming into contact with one part of the grinding disc rotating in one direction and a further part of the cutting edge coming into contact with part of the grinding disc rotating in the opposite direction.

A preferred embodiment, particularly suitable in this respect, and used for grinding scissors, is characterized in that the bottom of the slot in the extension piece inclines towards the grinding disc and is at an angle to the head face of the disc. When the leg of a pair of scissors is sideways held on a wall of the slot with the edge to be ground on the bottom of the slot, it is automatically 3,334,446 Patented Aug. 8, 1967 ensured that only one side of the head face of the grinding disc is engaged during the grinding process.

This reliable operation can also be obtained in grinding knives, since the sides of the connecting piece between the extension piece and the housing in the slot between the lower side of the extension piece and the wall of the motor housing incline towards the grinding disc.

The invention will now be described with reference to the drawing, which shows an embodiment of the invention.

FIG. 1 is a side view of a grinding device.

FIG. 2 is a plan view.

FIG. 3 is partly an end elevation and partly a sectional View taken on the line IIIIII .in FIG. 2 and FIG. 4 is a plan view of a leaf spring used in the grinding device.

Referring to the figures, reference numeral 1 designates the motor housing, one half of its upper surface being designated by 2 and the other half by the reference numeral 3. Above the last-mentioned faces there is arranged an extension piece 4, the lower walls 5 and 6 of which include one each side a guide slot 7 and 8 respectively with the upper faces 2 and 3 respectively of the housing 1. A knife can be inserted from the right-hand side and from the left-hand side into said slots in order to grind or polish the two sides, it being only necessary for the side face of the knife to be put in fiat position on one of the walls 2, 3 inclined towards the grinding disc, so that the cutting edge touches the upper face of the grinding disc 9. From FIG. 3 it is apparent that the grinding disc is urged downwards against the action of a spring 10, while the inner wall of the tray-shaped support 11 of the grinding disc 9 is guided along the outer wall of the tray-shaped end 12 of the rotating spindle 13, which forms at the same time a cup for the spring 10. The support 11 is carried along during the rotation of the spindle 13, since the later has a polygonal section and is taken with close fit through the opening 14 of the bottom of the support 11.

From FIG. 4 it will be seen in particular that the lower sides 5 and 6 of the extension piece 4 incline towards each other in downward direction and form the slots 7 and 8, while the central portion is provided with a transverse slot 15 which cuts the extension piece 4 above the head face 16 of the grinding disc 9. Consequently, the grinding disc is accessible at this place to a tool, for example the leg of a pair of scissors introduced into the slot 15, so that the cutting edge of the tool can be ground. On the side opposite said cutting area the extension piece 4 is fastened to the side 17 of the motor housing 1 (see FIGS. 2 and 3).

The side faces 18 and 19 of the slot 15 have different inclinations so that different angles of cutting can be ground by applying the leg of the scissors with one of the side faces at will to one of said walls. The bottom 20 of the slot 15 inclines towards the grinding disc 9. From FIG. 3 it will be seen in particular that. the cutting side of the limb of the scissors or of a similar instrument can be simply put on the bottom 20 along the line which is extended in FIG. 3 by a broken line 21, while the edge to be ground can come into contact invariably on side with the upper face 16 of the grinding disc 9 and mainly along the edge thereof. Consequently, grinding is always performed in the same direction when the limb of the scissors urged against the bottom of the slot is moved back and forth.

The same result is obtained when a tool for example a knife is placed in one of the slots 7, 8, since the sides 22, 23 of the connecting piece 24 between the extension piece 4 and the motor housing 1 incline towards the grinding disc (see also the extended broken lines 22, 23 in FIG. 2). By putting the cutting edge of the knife on the inclining sides 22 and 23 and by moving the knife in the longitudinal direction back and forth, a completely reliable grinding effect is obtained, without the need for technical insight of the user. From the figures of the drawings it will furthermore be seen that the motor housing as a whole is formed in a frusto-conical shape, while the connecting piece 24 between the extension piece 4 and the housing is fastened by a downwardly projecting tag 25 (see FIG. 3) at the center to a longitudinal side of the housing 1 by means of a screw 26, so that the whole eX- tension piece is detachable. The grinding disc 9 is located at the edge of the opposite side. The lower part of the housing is formed by an elongated tray 27 having upright side walls, which tray is detachable from the upper part of the housing, so that the two halves of the housing, as well as the extension piece, can he made cheaply as separate moulded pieces for example of a synthetic material. This shape is at the same time very suitable for use as a small household apparatus, which can be taken for example in the left hand on the end wall 28, so that the fingers extend along the wall 7 and one finger can easily actuate the press button 29 for switching the motor on and off; said switch is provided beneath the connecting tag 25 in the wall 7 of the housing. At one end of the tray 27 there is provided the passage 30 of the electric supply conductor.

In order to arrange the blade of a knife for grinding on the sides 2 or 3 easily in the correct direction, a leaf spring 31 or 32 is provided in each slot 7 or 8, the end of said spring projecting towards the longitudinal side of the slot being bent back towards the lower face or 6 respectively of the extension piece 4, so that the blade of the knife can be easily inserted and Will arrive in the correct position. The pressure is exerted by the spherical elevations 35 in each leaf spring (see also FIG. 4). The central portion of the spring is fastened to the housing 1 by clamping it below the connecting piece 24 of the extension piece, while a lug 38 is taken through a square opening 37 in thespring and is accommodated in a cavity 39 of the upper face of the housing.

What is claimed is:

1. A sharpening device for knives, scissors and the like comprising a housing having sloping, converging top surfaces, a grinding member in said housing located at the juncture of said top surfaces, an extension element having a front and back and being removably positioned above said top surfaces having lower walls conforming to but spaced from the sloping, converging top surfaces to form guide slots, a further guide slot inclined downwardly from back to front and part of said further guide slot directly over said grinding member being completely open; and a downturned flange on said extension element perpendicular to the plane of the latter, said flange being complementary and connected to a part of said housing formed in the shape of a frusto-pyramid.

2. A sharpening device for knives, scissors and the like comprising a housing having sloping, converging top surfaces, a grinding member in said housing located at the juncture of said top surfaces, an extension element removably positioned above said top surfaces having lower walls conforming to but spaced from the sloping, converging top surfaces to form guide slots, 21 further guide slot having part thereof extending entirely through said extension element in a generally vertical plane, and a leaf spring in at least one of said guide slots, the end of said spring being bent back toward the adjacent lower wall of said extension element.

3. A sharpening device for knives, scissors and the like as claimed in claim 2 wherein said leaf spring is provided with two wings extending in opposite directions in said guide slots, and means for clamping the central portion of said spring below said extension element.

References Cited UNITED STATES PATENTS 2,522,942 9/1950 Gillen 51--128 2,722,783 11/ 1955 ORussa 51l02 2,949,709 8/1960 Angelis 51-128 HAROLD D. WHITEHEAD, Primary Examiner. 

1. A SHARPENING DECIVE FOR KNIVES, SCISSORS AND THE LIKE COMPRISING A HOUSING HAVING SLOPING, CONVERGING TOP SURFACES, A GRINDING, MEMBER IN SAID HOUSING LOCATED AT THE JUNCTURE OF SAID TOP SURFACES, AN EXTENSION ELEMENT HAVING A FRONT AND BACK AND BEING REMOVABLY POSITIONED ABOVE SAID TOP SURFACES HAVING LOWER WALLS CONFORMING TO BUT SPACED FROM THE SLOPING, COVERGING TOP SURFACES TO FORM GUIDE SLOTS, A FURTHER GUIDE SLOT INCLINED DOWNWARDLY FROM BACK TO FRONT AND PART OF SAID FURTHER GUIDE SLOT DIRECTLY OVER SAID GRINDING MEMBER BEING COMPLETELY OPEN; AND A DOWNTURNED FLANGE ON SAID EXTENSION ELEMENT PERPENDICULAR TO THE PLANE OF THE LATTER, SAID FLANGE BEING COMPLEMENTARY AND CONNECTED TO A PART OF SAID HOUSING FORMED IN THE SHAPE OF A FRUSTO-PYRAMID. 